1. Field of the Invention
This invention relates to an optical plug for attachment to terminal ends of optical fibers and an optical connector comprising the optical plug and a receptacle mated and connected with each other.
2. Prior Art
FIGS. 11A and 11B illustrate an example of the conventional construction of such optical plug (see Japanese Patent Application Publication No. 2001-21767, for example), FIG. 11A being a plan view while FIG. 11B is a side view, partly in cross-section taken along the line 11B–11B′ in FIG. 11A. This optical plug 10 includes a body 20 and a tubular main cover 30 slidably mounted over the body 20 with an optical fiber cable 40 inserted into the body from the rear face thereof.
The body 20 is formed in its front face 20a with a recess 21, from the bottom wall 21 a of which ferrules (tubular members) 22 are formed to protrude in a forward direction. The face 20a of the body confronting the receptacle will be referred to as “front face” hereinafter. The term “forward direction” as well as the term “forward” or “forwardly” mean hereinafter a direction from the rear face toward the front face of the body, so that the direction opposite to the forward direction is also referred to hereinafter the term “rearward direction” as well as the term “rearward” or “rearwardly”. In this example, two ferrules 22 are disposed in juxtaposition with their forward ends 22a extending forwardly by a length L1 of the front face 20a of the body 20.
The optical fiber cable 40 is introduced through a rear end opening 30b of the cover 30 into the body 20 with the two optical fibers (optical fiber cores) 42 having their claddings 41 stripped off being inserted into the respective ferrules 22 with the forward ends 42a of the fibers flush with the forward ends 22a of the ferrules 22 and exposed. The reference number 50 in FIG. 11B indicates a retainer adapted to bite into the claddings 41 to fix the optical fibers 42 in place.
The body 20 is further formed on the top surface thereof adjacent its forward end with a locking protrusion 23 such that upon the optical plug 10 being inserted into the opening of a mating receptacle (not shown), a locking piece provided in the receptacle is engaged with the locking protrusion 23 to prevent withdrawal of the optical plug 10 and maintain it in mating connection with the receptacle. The optical plug and the receptacle thus form an optical connector.
Additionally, the cover 30 has a pair of actuator pieces 31 extending from the forward end 30a thereof on the opposite sides of the locking protrusion 23 (see FIG. 11A) and the actuator pieces 31 are formed on their opposing inside surfaces with mountain-like (trapezoidal) projections 32.
These projections 32 constitute the dissolving means for dissolving the engagement of the locking protrusion 23 of the body 20 with the locking piece of the receptacle when withdrawing the optical plug 10 from the receptacle. More specifically, when withdrawing the optical plug 10 from the receptacle, the cover 30 mounted over the body 20 is first slidingly moved rearwardly relative to the body 20, that is, in the direction of withdrawal whereby the locking piece wider than the locking protrusion 23 is forcedly lifted up by the pair of projections 32 out of engagement with the locking protrusion 23 to permit the withdrawal of the optical plug 10 from the receptacle.
It is to be noted here that when the optical plug 10 is mated with the receptacle, the pair of ferrules 22 are each fitted into a corresponding one of a pair of sleeves disposed in the opening of the receptacle whereby the optical fibers 42 are positioned in place to insure good optical connection.
As discussed above, the prior art optical plug 10 includes the ferrules 22 mating with the sleeves of the receptacle, the terminal ends of the optical fibers 42 being inserted and held in the ferrules 22 with the forward ends 42a of the fibers flush with the forward ends 22a of the ferrules 22 and the ferrules and fibers projecting barely forwardly of the front face 20a of the body 20.
Due to this, there was a possibility that the fiber ends 42a might be damaged or otherwise impaired during the handling of the optical plug 10, resulting in an increase in the optical coupling loss and hence deterioration in the performance.
In view of this, in the optical plug of such type, it has been proposed that a protective cap be provided so that it may be fitted over the forward ends of the fibers to protect them when the plug is in the unmated state (not in mating engagement with the receptacle) (see Japanese Patent Application Publication No. 2001-290046, for example).
However, in the system in which a protective cap be provided separately from the optical plug so that the fiber ends may be to protected from being damaged by fitting the cap over the fiber ends, the operation of attaching and detaching the protective cap was required when inserting and withdrawing the optical plug into and from the receptacle. In addition, such operation was also required during the inspection step, for example of the manufacturing process and found troublesome and time-consuming.
Furthermore, such protective cap had the drawback of being vulnerable to loss because it was separate from the optical plug.